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From: "dberlin at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/19038] [4.0 Regression] out-of ssa causing loops to have more than one BB Date: Sun, 26 Dec 2004 01:09:00 -0000 [thread overview] Message-ID: <20041226010946.22448.qmail@sourceware.org> (raw) In-Reply-To: <20041216155140.19038.dje@gcc.gnu.org> ------- Additional Comments From dberlin at gcc dot gnu dot org 2004-12-26 01:09 ------- Just to followup on irc discussions. Being able to coalesce this may require moving to a different out-of-ssa algorithm that is better at coalescing. All of the below take different approaches to the coalescing problem, however, they may provide some insight as to whether/how these two variables can be coalesced. The briggs one (which is what morgan is based on, which is what the comments claim is used) is known not to coalesce a significant number of variables. A comparison of the two major algorithms for out-of-ssa (briggs and sreedhar's) can be found at http://www.is.titech.ac.jp/~sassa/papers-written/sassa-kohama-ito-ipsi04.pdf Sreedhar's removes roughly 80% more copies than brigg's algorithm. Note that the authors propose their own algorithm, even though it does significantly worse than sreedhars, so i don't consider it a serious contender here. Sreedhar's can be found at http://tinyurl.com/5axtl i have a copy of the paper if you have no access. In addition, yet another different approach to out-of-ssa coalescing was presented at cgo 2004. http://www.cgo.org/cgo2004/papers/21_14_rastello_f_revised.pdf I mention it because it supposedly can coalesce even more than sreedhar's algorithm is able to. I point these out only as references to hopefully be able coalesce these variables. I don't believe totally rewriting out-of-ssa would be apropos for 4.0 unless the new algorithm is significantly simpler, etc (maybe one of the above would be, i don't know). -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19038
next prev parent reply other threads:[~2004-12-26 1:09 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2004-12-16 15:52 [Bug rtl-optimization/19038] New: Loop header copying dje at gcc dot gnu dot org 2004-12-16 21:39 ` [Bug rtl-optimization/19038] " dje at gcc dot gnu dot org 2004-12-16 22:55 ` steven at gcc dot gnu dot org 2004-12-17 4:04 ` pinskia at gcc dot gnu dot org 2004-12-17 4:05 ` pinskia at gcc dot gnu dot org 2004-12-17 4:16 ` pinskia at gcc dot gnu dot org 2004-12-17 4:28 ` pinskia at gcc dot gnu dot org 2004-12-20 18:25 ` [Bug tree-optimization/19038] [4.0 Regression] out-of ssa causing loops to have more than one BB pinskia at gcc dot gnu dot org 2004-12-20 19:04 ` pinskia at gcc dot gnu dot org 2004-12-20 19:23 ` pinskia at gcc dot gnu dot org 2004-12-20 19:47 ` pinskia at gcc dot gnu dot org 2004-12-22 19:03 ` steven at gcc dot gnu dot org 2004-12-23 2:41 ` pinskia at gcc dot gnu dot org 2004-12-23 15:19 ` dje at gcc dot gnu dot org 2004-12-23 16:00 ` steven at gcc dot gnu dot org 2004-12-24 12:13 ` mustafa at il dot ibm dot com 2004-12-24 12:42 ` steven at gcc dot gnu dot org 2004-12-24 12:46 ` steven at gcc dot gnu dot org 2004-12-24 12:52 ` steven at gcc dot gnu dot org 2004-12-24 12:55 ` steven at gcc dot gnu dot org 2004-12-26 1:09 ` dberlin at gcc dot gnu dot org [this message] 2004-12-26 15:06 ` pinskia at gcc dot gnu dot org 2004-12-27 21:08 ` law at redhat dot com 2004-12-28 8:22 ` law at redhat dot com 2004-12-28 9:18 ` law at redhat dot com 2004-12-28 23:32 ` law at redhat dot com 2004-12-29 19:33 ` steven at gcc dot gnu dot org 2004-12-29 20:50 ` pinskia at gcc dot gnu dot org 2004-12-29 20:52 ` pinskia at gcc dot gnu dot org 2004-12-29 21:06 ` law at redhat dot com 2004-12-30 17:27 ` pinskia at gcc dot gnu dot org 2004-12-30 18:39 ` law at redhat dot com 2004-12-30 18:49 ` pinskia at gcc dot gnu dot org 2004-12-30 21:51 ` pinskia at gcc dot gnu dot org 2005-01-04 4:04 ` law at redhat dot com 2005-01-04 4:10 ` pinskia at gcc dot gnu dot org 2005-01-10 20:02 ` pinskia at gcc dot gnu dot org 2005-01-12 13:34 ` amacleod at redhat dot com 2005-01-18 0:50 ` [Bug tree-optimization/19038] [4.0 Regression] ivopts " pinskia at gcc dot gnu dot org 2005-01-18 5:02 ` law at redhat dot com 2005-01-19 22:50 ` cvs-commit at gcc dot gnu dot org 2005-01-19 23:25 ` [Bug tree-optimization/19038] [4.0 Regression] out of ssa " pinskia at gcc dot gnu dot org 2005-01-19 23:34 ` pinskia at gcc dot gnu dot org 2005-01-20 0:31 ` pinskia at gcc dot gnu dot org 2005-01-20 0:47 ` pinskia at gcc dot gnu dot org 2005-01-20 1:15 ` pinskia at gcc dot gnu dot org 2005-01-21 13:18 ` steven at gcc dot gnu dot org 2005-01-21 13:22 ` rakdver at atrey dot karlin dot mff dot cuni dot cz 2005-01-21 13:27 ` steven at gcc dot gnu dot org 2005-01-21 13:29 ` [Bug tree-optimization/19038] [4.0 Regression] tree-ssa " steven at gcc dot gnu dot org 2005-01-21 19:19 ` dberlin at gcc dot gnu dot org 2005-01-22 1:51 ` dberlin at gcc dot gnu dot org 2005-01-22 16:48 ` cvs-commit at gcc dot gnu dot org 2005-01-22 16:49 ` dberlin at gcc dot gnu dot org
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